"What are you some kinda sissy?" I suggested once to an acquaintance that he could sign his child up for martial arts because he appeared to be quite the athlete. The guy got pretty pissed off at the idea of helping his child develop physical skills.

"I don't do martial arts I do football and wrestling!" what's with the testosterone around here?

"This is my friend. He does martial arts. He's a ninja/he can beat you/20 guys up." this is pretty dangerous. If someone suggests this, it probably means they just want you around so they can start ****.

OH and the best one I've gotten:

"Why couldn't you do something cool like BJJ?" to which I respond to them with: "well if rolling around on the floor without a shirt on with another dude is what you're into..."